The present invention relates to a uniform speed joint and an axial piston pump using the joint and, more particularly, to a uniform speed joint suitable for connecting a driving member and a driven member at highly precisely uniform speed and an axial piston pump using the joint.
Universal joints in each of which a driving member and a driven member are connected through drive pins the ends of which are fixed to the driving member and the other ends of the drive pines are slidably inserted in spherical bearings the circumference of which are engaged with the driven member were invented by inventors including the inventor of the present application, which universal joints are known in JP A 63-308220 or JP B 4-72072, for instance.
Further, an invention by which the prior arts are improved further and uniformity in speed of a joint portion is improved was made by inventors including the inventor of the present application, which invention is known in JP A 5-263759. In this invention, drive pins are slidably inserted in a driving member, spherical head portions each are made in one piece with the drive pin, and a universal joint is constructed by engaging them with a driven member.
The former universal joint is constructed so that a pitch circle difference of drive pins changing in position according to change in inclination angle between the driving member and the driven member is absorbed. However, since the driving member and driven member are connected by a pair of the drive pins, speed change takes place twice per one revolution. Therefore, the speed becomes nearly uniform, but it has deficiency that the rotation can not be transmitted at precisely uniform speed. Accordingly, problems such as mechanical vibrations or rotation noises are not solved.
In the latter universal joint, since bending stress necessary to transmit rotation is applied to the drive pins, slide resistance is large and, in particular, it becomes rotation load at high speed rotation whereby a follow-up property becomes bad. Therefore, in this case, also, even if rotation becomes uniform, problems such as mechanical vibrations and rotation noises are not solved.